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Method and apparatus for processing digital audio signal

a digital audio and audio signal technology, applied in the field of digital audio signal processing methods and apparatuses, can solve the problems of poor presence or reality of audio contents reproduced from digital audio signals, and not enough compensation

Inactive Publication Date: 2010-01-14
JVC KENWOOD CORP A CORP OF JAPAN
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0010]It is a first object of this invention to provide a method of processing a digital audio signal to effectively enhance the quality of audio contents represented by the digital audio signal.
[0011]It is a second object of this invention to provide an apparatus for processing a digital audio signal to effectively enhance the quality of audio contents represented by the digital audio signal.
[0018]This invention shapes the waveform represented by the input digital audio signal, and provides the following advantage. The effect of the waveform shaping on the input digital audio signal is more uniform than that of a waveform shaping process responsive to a peak-corresponding sample only.

Problems solved by technology

Since the digital audio signal lacks high-frequency-corresponding components, audio contents reproduced from the digital audio signal tend to be poor in presence or reality.
The above signal processing in the method and the apparatus of U.S. Pat. No. 7,024,260 can not sufficiently compensate for such differences in time position and value between local maximums and minimums in the waveform represented by the digital audio signal and those in the waveform represented by the analog audio signal since the time-position differences are not considered.

Method used

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  • Method and apparatus for processing digital audio signal
  • Method and apparatus for processing digital audio signal
  • Method and apparatus for processing digital audio signal

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first embodiment

[0026]FIG. 1 shows a digital audio signal processing apparatus 100 according to a first embodiment of this invention. The apparatus 100 includes a memory (a buffer) 101, a maximum detecting section 102, a minimum detecting section 103, a peak-value interpolating section 104, a peak-position measuring section 105, an inter-peak interval measuring section 106, an adder 107, a coefficient table selecting section 108, and a harmonic generating circuit 109.

[0027]The memory 101 receives an input digital audio signal formed by a sequence of samples having values representing a waveform of an original analog audio signal from which the input digital audio signal is generated through analog-to-digital conversion at a prescribed sampling frequency. Each of the samples has a predetermined number of bits. The samples are spaced at intervals equal to the prescribed sampling period (the reciprocal of the sampling frequency). The memory 101 stores a predetermined number of latest samples of the in...

second embodiment

[0074]FIG. 6 shows a digital audio signal processing apparatus 200 according to a second embodiment of this invention. The apparatus 200 is similar to the apparatus 100 (see FIG. 1) except for design changes mentioned hereafter.

[0075]The apparatus 200 includes a computer, a digital signal processor, or a similar device having a combination of an input / output port 201, a CPU 202, a ROM 203, a RAM 204, and a storage unit 205. The input / output port 201 receives an input digital audio signal. The apparatus 200 converts the input digital audio signal into an output digital audio signal through a waveform shaping process. Specifically, the apparatus 200 corrects specified ones among samples of the input digital audio signal while holding the other samples as they are. The corrected samples and the non-corrected samples constitute the output digital audio signal. The input / output port 201 feeds the output digital audio signal to an apparatus output terminal or an external device (not shown...

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Abstract

There is a sequence of samples having values representative of a waveform. Peak-corresponding samples are detected which correspond to respective peaks including local maximums and local minimums in the waveform. An ideal waveform peak is estimated from the value of each detected peak-corresponding sample and values of samples temporally adjacent to the detected peak-corresponding sample through interpolation. A time interval between every two temporally adjacent estimated peaks is calculated. One is selected from coefficients in accordance with the calculated time interval. The value of each detected peak-corresponding sample and values of samples temporally adjacent to the detected peak-corresponding sample are corrected in response to the selected coefficient, the value of an estimated peak corresponding to the detected peak-corresponding sample, and a time position of the estimated peak.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]This invention relates to a method and an apparatus for processing a digital audio signal to enhance the quality of audio contents represented by the digital audio signal.[0003]2. Description of the Related Art[0004]Typical conversion of an analog audio signal to a digital audio signal has a step of periodically sampling the analog audio signal at a prescribed sampling frequency to generate analog samples, and a step of changing the analog samples into corresponding digital samples constituting the digital audio signal. According to the Nyquist Theorem, the frequency of audio contents represented by the digital audio signal is limited to lower than the Nyquist frequency equal to a half of the sampling frequency.[0005]The CD (compact disc) standards prescribe that a digital audio signal which results from analog-to-digital conversion of an analog audio signal at a sampling frequency of 44.1 kHz and a quantization bit num...

Claims

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Application Information

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IPC IPC(8): G06F17/00G10L21/0388
CPCG11B20/10009G11B20/10037G11B2020/10583G11B2020/10546G11B2020/10555G11B20/10527
Inventor OOUE, NAOYA
Owner JVC KENWOOD CORP A CORP OF JAPAN